By Heather Sadusky

This story begins with a question from a caller to the television newsroom.

Where did all the Monarch butterflies in my yard from last year go?

Well, it turns out that Monarch butterfly populations are in fact greater this year than they have been in the past two years.

Their population tends to fluctuate, and the summer season isn’t over yet, but some collectors of the Illinois Butterfly Monitoring Network have noted they saw more in one day this year than all of last.

However, when looking at the long-term trend over 10 to 15 years, the Monarch butterfly population has been steadily declining.

A recent study indicated the possible negative effects road salt can have on butterflies, but Monarch specialist Doug Taron from the Peggy Notebaert Nature Museum said that wouldn’t even make his list of problems.

The biggest issue is the Monarch’s loss of food and habitat, the milkweed plant.

With recent developments in agriculture, “round-up ready” corn has become a dominant crop because it’s been genetically modified to be resistant to the pesticide Round-Up.

This means fields of round-up ready corn can be treated with the pesticide and remain unaffected, while all the other “weeds” and undesirable pests are killed off.

This includes milkweed, the Monarch butterfly’s only food source.

Additionally, the push for biofuels several years ago caused fields to be cleared for growing biofuel crops (soy, corn, etc), further diminishing milkweed from the landscape.

Other occurrences like disease and predation can have an effect on Monarch populations, but are part of the natural order.

Some, though, believe that the practice of rearing monarchs for celebrations such as weddings is spreading disease, which is not entirely unfounded.

Today, we are in the middle of a generation of Monarch butterflies who originated in Illinois and will die in Illinois, but not after laying their eggs that will hatch in about 4-6 weeks.

Those offspring will become adults during a time of year when there is less sunlight, causing them to live longer and to fly south, migrating to Mexico for our winter.

The whole circuit from Illinois to Mexico and back across the span of a year takes about four generations of Monarch butterflies to complete.

While scientists can’t pinpoint an exact, direct cause for the decrease in populations, continue planting your milkweeds if you’d like to continue seeing Monarchs!

The Peggy Notebaert Nature Museum hosts butterfly releases every day at 2 p.m.